The short peptide RGDS (Arg-Gly-Asp-Ser) is a synthetic cell adhesion factor. RGDS is known to mediate cell adhesion to several extracellular matrix components as well as cell–cell interactions. The RGDS peptide has been shown to interact directly with and activates caspases 8 and 9, which indicates an unexpected pro-apoptotic effect due to an intracellular action.